Optical beamsplitters are known. Some beamsplitters are made by cementing two prisms together with a reflective film in between. The reflective film typically extends between opposite edges of the beamsplitter. See e.g. U.S. Pat. No. 7,329,006 (Aastuen et al.)
Lenses, including compound lenses in which two or more simple lenses are cemented together, are also known. U.S. Pat. No. 5,654,827 (Reichert) discusses lenses in which the lens is divided into two parts by a beamsplitter.
Head-Up Displays or Head-Mounted Displays (collectively referred to herein as HUDs) can project an image that fills all or part of a user's field of view. Some HUDs use a combiner optic that integrates the projected image with the usual image of the external environment. In some cases, the HUD is a Near-Eye Display (NED), which may have a form factor similar to that of eyeglasses. See e.g. U.S. Pat. No. 6,353,503 (Spitzer et al.).